The molecular organization of the photosynthetic membrane and its components will be investigated by high resolution electron microscope techniques. Three systems will be used for study: a bacterial photosynthetic membrane, photosynthetic membranes from higher plants in which ordered lattices of membrane subunits have been induced, and a reconstituted system containing a chlorophyll-protein complex in an artificial lipid bilayer. Each of these systems has shown a high degree of two-dimensional order, and this characteristic will be exploited in analyzing their detailed substructure. Electron and optical diffraction techniques, combined with computer analysis of electron micrographs, will be used to form high resolution synthesized images of the membrane systems. It is expected that these high resolution maps will provide insights into the nature of the photosynthetic process and the structure of biological membranes in general.